EP0007389B1 - Power recovery system and method therefor - Google Patents

Power recovery system and method therefor Download PDF

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Publication number
EP0007389B1
EP0007389B1 EP79101346A EP79101346A EP0007389B1 EP 0007389 B1 EP0007389 B1 EP 0007389B1 EP 79101346 A EP79101346 A EP 79101346A EP 79101346 A EP79101346 A EP 79101346A EP 0007389 B1 EP0007389 B1 EP 0007389B1
Authority
EP
European Patent Office
Prior art keywords
expander
generator
interrupting
waste heat
fluid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP79101346A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0007389A1 (en
Inventor
Carl H. Geary
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Carrier Corp
Original Assignee
Carrier Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carrier Corp filed Critical Carrier Corp
Priority to AT79101346T priority Critical patent/ATE2039T1/de
Publication of EP0007389A1 publication Critical patent/EP0007389A1/en
Application granted granted Critical
Publication of EP0007389B1 publication Critical patent/EP0007389B1/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/18—Structural association of electric generators with mechanical driving motors, e.g. with turbines
    • H02K7/1807—Rotary generators
    • H02K7/1823—Rotary generators structurally associated with turbines or similar engines
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/10—Structural association with clutches, brakes, gears, pulleys or mechanical starters
    • H02K7/104—Structural association with clutches, brakes, gears, pulleys or mechanical starters with eddy-current brakes
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/04—Control effected upon non-electric prime mover and dependent upon electric output value of the generator

Definitions

  • This invention relates to a system for recovering power from a relatively high temperature waste heat fluid and in particular to such a system utilizing a dynamic brake to control the speed of the expansion means employed in the power recovery system.
  • waste head fluids are generated.
  • the waste heat fluid in some instances has been employed to drive a turbomachine such as a fluid expander.
  • the expander has heretofore been directly coupled to a compressor and operates as the prime mover therefor.
  • the compressor is generally employed to provide substantial quantities of high pressure air required in the catalytic cracking process.
  • refinery floor space is generally at a premium.
  • a process shutdown results in a severe economic penalty and thus is avoided if at all possible.
  • the waste heat fluid furnished to the expander is a high mass flow, low density, high specific volume fluid. Generally, the fluid is furnished through relatively large conduits, as for example 121.9 cm (48 inch) diameter pipes.
  • the compressor When the expander has been connected to a compressor, the compressor has operated as a power absorbing load which has enabled the expander to safely dissipate trapped energy.
  • the expander generator string might accelerate rapidly and exceed safe operating speeds due to the absence of a power absorbing load.
  • the generator inertia would not, in the absence of an electrical load, prevent the expander string from obtaining unsafe speeds.
  • expander-generator strings have always included compressors to insure that a power abosorbing load is continuously attached to the expander.
  • a synchronous generator is extremely speed sensitive. Due to the properties of the fluid delivered to the expander, the expander's speed could not be accurately controlled to permit the synchronous generator to be connected to a power supply grid.
  • United States Patent No. 1,643.213 discloses a steam turbine driving a generator.
  • the turbine-generator string includes an electrical brake to govern the speed of the string to maintain substantially constant velocity and thus voltage output.
  • the excitation of the.brake coils is varied, depending on sensed speed changes, to maintain the desired constant velocity.
  • the brake functions to maintain a desired steady state speed.
  • the steam turbine disclosed in the Kane patent differs from the expander utilized in a waste heat power recovery system in many respects.
  • the steam turbine generally receives steam at relatively high pressure, high density and low mass flow. If the load on a generator driven by such a turbine were suddently removed, a valve located upstream of the turbine can be closed to terminate flow of steam to the turbine.
  • the valve can be used since only a relatively small quantity of steam will be trapped between the valve and turbine inlet. The energy contained in the trapped steam can be readily dissipated, without accelerating the turbine-generator string to unsafe limits.
  • United States Patent No. 1,740,356 discloses a system for regulating a turbine driven generator supplying a variable load system.
  • An electromagnetic brake is used to provide a governor function by smoothing out the load fluctuations by providing an artificial load to replace the load removed from the system.
  • U.K. Patent Specification No. 6407 discloses a turbine driven generator supplying a varying load in the nature of light fixtures which are turned off and on by the customer. In order to maintain the voltage constant an eddy current brake is used as a governor to maintain a constant load, the braking device taking the place of steam admission regulators.
  • U.K. Patent Specification No. 1,309,589 discloses a power recovery system for a catalytic cracking process in which flue gas from the catalyst regenerator is passed through a turbine coupled to a non-synchronous generator. It is suggested that the power recovery portion of the system can be stopped instantaneously by bypassing the motive fluid around the turbine. There is no braking structure for the turbine-generator string so that the system is stopped solely by bypassing the motive fluid. Where the motive fluid supply lines are four feet in diameter, for example, the inertia of any valves would make instantaneous opening and closing impossible so that generator damage could result before shutdown can be achieved solely through the closing of the supply valve and the opening of the bypass line valve.
  • the expander used in a power recovery system receives a low pressure, high mass, low density fluid. Any trapped fluid will cause rapid acceleration of the expander-generator string. Thus, relatively slow acting valves cannot be used to prevent abrupt acceleration of the string upon a sudden removal of a power absorbing load, and a system that can readily absorb power during transient conditions is required.
  • a system for recovering power from a relatively high temperature waste heat fluid which includes expansion means to receive the relatively high temperature fluid supplied through a normally open cut-off valve.
  • the expansion means is operatively connected to an electrical power generating means, with the expansion means driving the generating means as a result of the expansion of the high temperature fluid therethrough.
  • Brake means is operably connected to the expansion means to regulate the speed of the expansion means when the expansion means is operating at other than steady state conditions and by-pass means is provided to release fluid trapped between the cut-off valve and the expander when the cut-off valve is closed.
  • the invention provides a system for recovering power from the waste heat fluid formed directly from the combustion of process gas and expanded through an expander drivingly connected to an electric power generating means for supplying electrical power to a load, normally open interrupting means being provided operable to interrupt the supply of fluid to the expander to reduce the drive to the generating means and normally closed by- pass means being provided upstream of the interrupting means to avoid interruption of the process when the interrupting means is operated characterised by the provision of second normally closed by-pass means connected between the interrupting means and the expansion means operable to release the fluid trapped between the interrupting means and the expander when the interrupting means is closed and electromagnetic braking means electrically operable to brake the generator means.
  • the single figure of drawing schematically illustrates a system for recovering power from a relatively high temperature waste heat fluid in accordance with the present invention.
  • power recovery system 10 includes an expander 12 coupled through a suitable speed reducing mechanism 16 to an electrical generator 14 which may either be an induction or synchronous generator.
  • the expander and generator are axially aligned and include a shaft 20 coupled to a dynamic power absorbing mechanism 22.
  • the power absorbing mechanism 22 is preferably an eddy current brake having excitation coils 24. Coils 24 are operatively engaged with a brake drum 26 mounted on the end of the shaft. The coils are energised by the supply of DC electrical power thereto to activate the eddy current brake. Eddy current brakes of the type described are manufactured and sold by the Eaton Corporation under the registered trademark "Dynamatic".
  • the control system for brake 22 includes a variable resistor 28 or other suitable controller which regulates the magnitude of the DC voltage furnished to coils 24.
  • the strength of the brake is a function of the magnitude of the DC voltage supply.
  • a switch 30 is connected in series with variable resistor 28 to selectively supply the DC voltage to the coils from a suitable DC source, such as battery pack 32.
  • the battery provides a DC voltage, for example 90 volts, to the coils through variable resistor 28.
  • generator 14 may serve as a source of DC power in lieu of battery pack 32. The utilization of generator 14 as the DC power source will produce regenerative braking.
  • Expander 12 is provided with a source of relatively high temperature waste heat fluid through inlet conduit or line 42.
  • the waste heat fluid is expanded through device 12 and exits therefrom through conduit 43.
  • Valve 40 is disposed in line 42 upstream from expander 12.
  • valves 44 and 46 are respectively disposed in lines 48 and 50 for a reason to be more fully explained hereinafter.
  • the generator delivers electrical power through electrical conductors 60 and 62 to an electrical load, represented by reference numeral 52.
  • the electrical load may include the electric motor employed to drive a compressor and may also include other electrically operated components in the plant, or in some instances, may include the commercial grid served by a public utility.
  • a load disconnect switch 58 is interposed in conductors 60 and 62 to remove the electrical load from the expander-generator string 12, 14.
  • a brake power switch 54 is interposed in lines 68 and 70.
  • Lines 68 and 70 furnish electrical power from lines 60 and 62 through a regulator and rectifier 56 and electrical conduits 72 and 74, to coils 24 of eddy current brake 22 for a reason to be more fully explained hereinafter.
  • control for brake 22 may include an inverter driver 82, a DC to AC inverter 84, a voltage regulator and rectifier 86, a capacitive storage bank 88, and a switch 90. These electrical elements are connected to battery pack 32 via electrical conductor 92. Elements 82, 84 and 86 multiply the DC voltage available from source 32 by a relatively large factor, as for example by a factor of ten. Capacitive storage bank 88 retains the amplified DC voltage and feeds same to coils 24 upon closure of switch 90. Switch 90 immediately closes upon the opening of switch 58.
  • the present invention includes a power absorbing brake operable when the expander is operating at other than normal operating conditions.
  • the phrase "other than normal operating conditions” shall include starting conditions, sudden unloading of the generator, and afterburn conditions all of which are transient, as opposed to steady-state, conditions.
  • the relatively high temperature waste heat fluid flows through line 38, valve 40, and line 42 to expander 12. Should it be necessary to suddenly disconnect the generator from the electrical load, it becomes necessary to immediately shutdown expander 12; valve 40 is closed, and valves 44 and 46 are opened. This results in the flow of fluid being directed through line 38, valve 46 and line 50 to a boiler 36.
  • valve 44 since valve 44 is opened, the relatively high temperature waste heat fluid captured between valve 40 and the expander 12 will escape. However, since mechanical actions are required to move the various valves in the desired sequence, a delay of two to three or sometimes even more seconds will occur before flow of fluid to the expander is actually terminated. During this relatively short period of time, the expander string may accelerate beyond safe operating speeds. Such an abrupt increase in the speed of the expander results from the high mass flow, high specific volume properties of the fluid. In addition, there will be a relatively large trapped volume of fluid between valve 40 and the expander due to the size of conduit 42; for example 48 inch diameter pipe is employed to deliver the fluid to the expander. Before valve 44 can fully open to exhaust the fluid, the fluid will enter the expander. Since the generator is "unloaded", the expander will accelerate very rapidly as the fluid continues to expand therethrough.
  • brake switch 54 of switch 90 is immediately closed to place a DC voltage on coils 24.
  • the DC voltage furnished to the coils may be obtained from generator 14 or from storage bank 88. If obtained from generator 14, the voltage is delivered through electrical conductors 60 and 62, 68 and 70 and 72 and 74 to coils 24.
  • Variable resistor 28 can be selectively controlled to permit a maximum DC voltage to flow to coils 24 of brake 22.
  • the eddy current brake has a characteristic that the brake torque produced is a function of the DC voltage applied to the coils.
  • a relatively high brake torque can be produced in a matter of a few milliseconds.
  • a step-up transformer may be added to the circuit to increase the magnitude of the DC voltage applied to coils 24 by some relatively large factor, as for example by a factor of ten. This, in turn, will increase the available brake torque to ten times maximum rating of the brake.
  • the brake can operate at ten times its maximum rated torque for a substantially greater period of time than that required to insure that the energy contained within the trapped gas will be dissipated.
  • Switch 90 may be closed in lieu of switch 54 to connect the storage bank directly to coils 24.
  • the use of the regenerative braking system can be established as "normal operation", with the use of the battery pack as the source of DC voltage being available as an emergency backup.
  • Switch 30 can be closed to provide the necessary DC excitation to coils 24 from battery pack 32 upon start-up. By connecting coils 24 with battery pack 32, the necessary excitation of the coils will be obtained.
  • resistor 28 can be suitably regulated to adjust the voltage furnished to coils 24, whereby the speed of the expander may be suitably regulated.
  • switch 30 may be closed to energize coils 24 of brake 22.
  • a fixed voltage signal can be supplied to the coils to establish a brake torque of a predetermined magnitude to absorb the extra power developed by expander 12 as a result of the addition of excessive energy to the waste heat fluid due to the occurrence of the afterburn.
  • eddy current brake 22 is further operable to bring the expander and generator to synchronous speed to enable an operator to connect the expander-generator string with the load.
  • variable resistor 28 can be adjusted to control the magnitude of the DC voltage to coils 24 to fine tune the speed of the expander. In effect, by varying the brake torque acting on shaft 20, the speed of the generator-expander string may be readily controlled. While various combinations of controls have been specifically described, other control arrangements may also be used to achieve the benefits of the present invention.
  • the power absorbing means 22 of the present invention achieves a multiplicity of functions in that it provides a fine tune speed control when expander 12 is driving a synchronous generator.
  • brake 22 eliminates the need for the expander to be directly coupled to a compressor.
  • the brake provides a readily available source to absorb power on an instantaneous basis should the normal load be abruptly disconnected from the expander-generator string.
  • dynamic power absorbing means 22 eliminates the need to oversize a generator coupled to the expander to provide means to dissipate the additional energy contained within the motivating fluid upon the occurrence of an afterburn.
  • Power absorbing means 22 effectively provides all the functions of the hereinabove described apparatus. It should be specifically understood that although system 10 has been specifically described relative to a catalytic cracking process, the present invention should not be limited thereto but may be satisfactorily employed in any other process wherein a relatively high temperature waste heat fluid is used as a source of energy.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)
EP79101346A 1978-05-08 1979-05-03 Power recovery system and method therefor Expired EP0007389B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT79101346T ATE2039T1 (de) 1978-05-08 1979-05-03 System und verfahren zur energierueckgewinnung.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US05/903,461 US4211932A (en) 1978-05-08 1978-05-08 Power recovery system
US903461 1978-05-08

Publications (2)

Publication Number Publication Date
EP0007389A1 EP0007389A1 (en) 1980-02-06
EP0007389B1 true EP0007389B1 (en) 1982-12-15

Family

ID=25417542

Family Applications (1)

Application Number Title Priority Date Filing Date
EP79101346A Expired EP0007389B1 (en) 1978-05-08 1979-05-03 Power recovery system and method therefor

Country Status (12)

Country Link
US (1) US4211932A (da)
EP (1) EP0007389B1 (da)
JP (1) JPS6038538B2 (da)
AR (1) AR220194A1 (da)
AT (1) ATE2039T1 (da)
AU (1) AU534558B2 (da)
BR (1) BR7902759A (da)
CA (1) CA1121454A (da)
DE (1) DE2964252D1 (da)
DK (1) DK153098C (da)
ES (1) ES480306A1 (da)
MX (1) MX145925A (da)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4352024A (en) * 1981-05-04 1982-09-28 Carrier Corporation Expander-generator control system
US4555637A (en) * 1982-07-26 1985-11-26 Acd, Inc. High speed turbogenerator for power recovery from fluid flow within conduit
US4791309A (en) * 1982-09-21 1988-12-13 Thamesmead Engineering Limited Electrical control systems
US4766362A (en) * 1986-11-24 1988-08-23 Simmonds Precision Products, Inc. Regulatable permanent magnet alternator
US5300819A (en) * 1992-03-24 1994-04-05 Industrial Technology Research Institute Automatic power regulator for induction type biogas generator
DE29720198U1 (de) * 1997-11-14 1999-03-25 Jenbacher Energiesysteme AG, Jenbach Stromerzeugungsanlage
JP2003116253A (ja) 2001-07-19 2003-04-18 Toshiba Corp タービン発電機設備およびその設置方法
WO2009038562A2 (en) 2007-09-19 2009-03-26 Utc Power Corporation Preventing overspeeding of a turbine driven generator
EP2295733A1 (de) * 2009-08-12 2011-03-16 Siemens Aktiengesellschaft Kraftwerksanlage und Verfahren zum Betreiben einer Kraftwerksanlage
JP5700237B2 (ja) * 2010-07-08 2015-04-15 株式会社Ihi 排熱回収装置
WO2017205397A1 (en) * 2016-05-24 2017-11-30 Scuderi Group, Inc. Method of utilizing a combined heat and power system to produce electricity for a wholesale electricity market

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB191506407A (en) * 1915-04-29 1916-03-23 British Thomson Houston Co Ltd Improvements in and relating to the Regulation of Dynamo Electric Machines.
US1740356A (en) * 1921-04-19 1929-12-17 Allis Chalmers Mfg Co Electrical power system
US2998539A (en) * 1957-12-16 1961-08-29 Prec Mecanique Labinal Devices for driving, especially alternators, at substantially constant speed from a variable speed shaft
US3219831A (en) * 1960-12-22 1965-11-23 Trw Inc Turboelectric space power plant
US3230381A (en) * 1964-02-24 1966-01-18 Sherman K Grinnell Electric power unit
GB1137317A (en) * 1967-05-18 1968-12-18 Elin Union Ag Fur Elek Sche In Improvements in or relating to gas turbine installations
DE2009711C3 (de) * 1970-03-02 1980-08-07 Oemv Ag Verfahren und Anlage zur Ausnutzung des Energieinhaltes des bei katalytischem Krackanlagen anfallenden Rauchgases
FR2296295A1 (fr) * 1974-12-23 1976-07-23 Semt Dispositif pour la production de puissance electrique a partir de l'energie recuperee sur les gaz d'echappement d'un moteur a combustion interne
US4117344A (en) * 1976-01-02 1978-09-26 General Electric Company Control system for a rankine cycle power unit
FR2355178A1 (fr) * 1976-06-18 1978-01-13 Anvar Dispositif regule de production d'energie electrique, tel que dispositif eolien

Also Published As

Publication number Publication date
ATE2039T1 (de) 1982-12-15
US4211932A (en) 1980-07-08
AU534558B2 (en) 1984-02-09
DK153098B (da) 1988-06-13
MX145925A (es) 1982-04-21
BR7902759A (pt) 1979-11-27
DK153098C (da) 1988-10-31
EP0007389A1 (en) 1980-02-06
AR220194A1 (es) 1980-10-15
JPS6038538B2 (ja) 1985-09-02
DK189179A (da) 1979-11-09
JPS54147337A (en) 1979-11-17
ES480306A1 (es) 1979-12-16
DE2964252D1 (en) 1983-01-20
AU4681479A (en) 1979-11-15
CA1121454A (en) 1982-04-06

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